Means for applying artificial respiration



Aug. 11,

Filed Feb.

V. R. BENNETT MEANS FOR APPLYING ARTIFICIAL RESPIRATION 4 Sheets-Shed: l

5 EH! BEA/N577;

INVENTOR.

Aug. 11, 1953 v, R. BENNETT 2,643,331

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Patented Aug. 11, 1953 MEANS FOR APPLYING ARTIFICIAL 1 RESPIRATION Vivian Ray Bennett, Angeles, Calif. Application February 1, 1950, Serial No. 141,748

11 Claims. (Cl. 12830) This invention relates to kinesitherapy; and

more particularly to the science of life extensions .by artificial respiration.

In the treatment for the control of poliomyelitis it is common practice to place the patient within a respirator whereby his chest is subjected alternately and at regularly repeated intervals to negative and positivepressureyto expand and contract the thoracic cage and thereby artificially induce the regular inhalation and exhalation steps of breathing which his paralyzed condition makes it impossible for'him to continue naturally. Whereas the requirements for different patients and, in fact, for each individual patient as his condition varies, are subject to a comparatively wide range of variation, in the usual case it is necessary to operate the conventional respirator so that the pressure therein alternates at regular intervals from minus 12 to 18 centimeters of water pressure to plus 2 to 3 centimeters of water, i. e., a pressure variation of approximately to 20 centimeters of water pressure. But in cases of unusually severe paralysis, or of especially severe or extensive congestion of the lungs; it becomes necessary, in: order to attain adequate ventilation of the lungs, to operate the respirator over a wider range of pressure variation by increasing the degree of negative pressure in order to cause a sufficient volume of respiration. Unfortunately, such treatment often proves inadvisable, or even dangerously severe in a large number of cases, as the excessively high degree of negative pressure necessary, often as high as to 27 cm. of water pressure, is apt to cause complications. The exact mechanism is not fully understood, but patients often will develop mucus, pulmonary edema, atelectasis or other conditions very detrimental to respiration.

One of the problems, therefore, for which a solution is provided in. the present invention is that of assuring adequate ventilation of the lungs of an iron-lung patient, without resorting to an excessive degree of negative pressure. It should be pointed out also that a high negative pres-' sure is usually diiilcult to maintain because of leaks around the collar seal and other parts.

A more detailed object in this connection is to supplement the normal respiratory action of a standard respirator by supplying synchronized intermittent positive pressure internally, so as to inflate the patients lungs.

In still further detail, the present invention seeks to supply the gas or gases to be inhaled at a pressure adequate to overcome the resistance of the upper respiratory tract, the tracheotomy tube, if one is being used, and aid in expanding the lung by internal pressure inflation,

Another object of my invention is to provide apparatus of a simple, durable, and thoroughly dependable nature by which improved methods of treatment can be carried out, and which is capable of being mounted upon and operably coupled to a standard respirator, for operation synchronously therewith, so simply and easily that interruption of the respirators normal functioning is unnecessary.

A further object is to provide apparatus of the general character indicated for providing intermittent positive pressure breathing in proper synchronism with a standard respirator, which permits the patient to exhale naturally into the atmosphere after each inspiration with virtual- -ly no pressure or flow resistance, and without any material waste of the gases being administered, and with a minimum amount of rebreathing.

A still further object is to make provision for ready adjustment of the accessory apparatus of the present invention, so that the pressure at which gas is administered can be regulated almost instantly, and thus insure against almost any clinical emergency, and to enable the accessory attachment to take over the entire responsibility of inducing breathing of a paralyzed patient as during respirator pressure failure emergencies, or to permit opening of the respirator for such functions as nursing care, medical treatment, transfer of the patient to another respirator, or even surgery.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of my invention which is illustrated in the drawings accompanying the forming part of the specification. It is to be understood that I do not limit myself to the showing made by the said drawings and description, as I may adopt variations of the preferred form within the scope of my invention as set forth in the claims.

- Referring to the drawings:

Figure 1 is a perspective view of a standard 'respirator having a respirator pressure attachment incorporating the principles of the present forming my improved method of administering artificial respiration which also constitutes a -portion of the present invention.

Figure 2 is an enlarged perspective view of the gas pressurizing assembly portion of the resplrator attachment of the present invention, showing the manner of its being mounted upon and of being synchronized into the cycle of the respirator. Portions of the figure are broken away and shown in section to reduce the size of the figure and the better to illustrate parts of the apparatus.

Figure 3 is an end elevation of the respirator and respirator attachment of Figure l, drawn to a slightly reduced scale, with parts broken away the better to reveal constructional detail.

Figure 4 is an enlarged detail view in vertical section taken upon the line 44 of Figure 3, to illustrate the clamp whereby the movable element of the auxiliary bellows is coupled to the oscillating lever of the respirators bellows operating mechanism.

Figure 5 is an enlarged detail view of the auxiliary bellows and associated portions of the gas pressurizing assembly of the respirator attachment.

Figure 6 is a longitudinal vertical sectional view of the pressure control. box assembly portion of the respirator attachment.

Figure 7 is an enlarged detail view in horizontal section taken on the line 1-1 of Figure '6, with the direction of view as indicated.

Figure 8 is a view in side elevation of the head assembly portion of the respirator attachment.

Figure 9 is an enlarged detail view in vertical section taken medially through a portion of the head assembly of Figure 8.

Figure 10 is a diagram illustrating schemati- 1 .cally the several portions of the positive pressure respirator attachment of the present invention, showing the manner of their association with each other and with the bellows of the respirator proper.

Figure 1 illustrates the manner which the positive pressure respirator attachment. of the present invention is mounted upon a standard respirator of conventional design. Whereas the conventional respirator chosen for illustration in conjunction with my positive pressure attachment is of the tank type adapted to receive the entire body of a patient with the exception of his head, commonly known in the trade as the Drinker-Collins respirator, or iron lung, it

should be understood that my respirator attachment is adaptable with equal facility and equal efliciency of operation upon respirators of other types.

The respirator chosen for illustration comprises a relatively large shell II adapted to be hermetically sealed so that a differential. in pressure between the interior and the exterior of the shell I I can be established. The shell is largeenough to receive the entire body of a patient with the exception of his head I2 which protrudes through one end I3 of the shell I I to which the-end I3 is preferably detachably secured, as by a plurality of clamps I4. Conventionally, a relatively large bellows I6 is mounted below the shell I I, the upper end or head ll of the bellows I6 being rigidly secured to the under side of the shell I I through which communication between the interior of the bellows I6 and the interior of the shell I I is established by a suitable port or passageway (not shown). The lower or movable head I8 of the bellows I6 is supported by a pitman arm I9 to which it is preferably rigidly connected and which extends rigidly upward. from a substantially horizontal lever 2I, one end' of which is 4 pivoted as by a pin 22 to one of the legs 23 of the frame 24 upon which the shell I I of the respirator is mounted. A driving motor 26 is supported upon a platform 21 also carried by the frame 24 and this motor is operably connected as by a belt 28 to a set of speed reduction gears (not shown) operable within a suitable gearbox 29 through one wall of which the driven shaft 3| extends to receive a crank 32 operably engaged with the lower end of a connecting rod 33. The upper end of the connecting rod 33 is pivotally connected to a crosshead 34 adjustably mounted upon the lever 2| beyond the pitman arm I9 thereon from the pivot pin 22. By sliding the crosshead 34 along the lever 2I toward or away from the-pivot pin 22, the distance through which the lever 2]. is .reciprocated each time the crank 32 makes a complete revolution is increased or decreased respectively as is also the length of stroke of the lower head I8 of the bellows I6. It is apparent, therefore,v that adjustment of the crosshead 34 attains variation of the quantity of air that it forces into the shell II and, during the next phase of its cycle of operation, that it withdraws from the shell II. It is likewise apparent that energization of the motor 26 results in attaining fluctuation of the air pressure within the shell II from anegative pressure caused by withdrawal of air from the shell I I as. the bellows I6- expands as the result of downward movement of its lower head -I8; and that. similarly positive pressure is attained within the shell II as the result, of collapsing of the bellows It coincident with the upward movement of the movable head It. The magnitude of both. these positive and negative pressures is determined by the positioning. of the crosshead 34 upon the lever 21, a looking screw preferably operated by a hand grip 36 being provided upon the screw to facilitate clamping the cross head 34 in selected position of adjustment upon the lever 2-I.

It. is customary medical proctice to treat for the control of poliomyelitis by placing a patient with his entire body except his head I2 within such ashell II and, after sealing the opening in the head end I3 thereof through which the patients head extends as by a flexible, impervious collar 2, to induce artificial respiration in the patient by operation of the bellows I6 in accordance with the hereinabove description. When the bellows I6 expanded, the consequent negative pressure created within. the-shell I I will cause the patients thoracic cage to expand in much the same manner as in natural breathing but without requiring any muscular activity on the patients part, thus compensatin for the inability of the paralyzed muscles of his respira- 1:01! system to function normally. Such expansion of his thoracic cage develops a partial vacuum within. the patients lungs, with the result that a. quantity of air will be drawn through the patients respiratory tract into the lungs, thereby oxygenating the patients lungs sufiiciently to prevent asphyxiation in most cases. However, as indicated in the objects of the pres- ..ent invention, as hereinabove recited, in extreme cases it frequently develops that sufficient oxygen to maintain life cannot be drawn into the patient's lungs in this manner without resorting to such extreme negative pressure that the lung tissues are. apt to be impaired, and it is for the purpose of overcoming this. and other disadvantages of conventional "iron lung practice that the apparatus of the present invention has been designed.

-work 26 of the respirator.

The positive pressure respirator attachment of the present invention comprises in general a gaspressurizing unit indicated in its entirety at 5|,

' unit 5| and to the pressure control box assembly V 52, as will be described in detail hereinbelow.

Referring first to Figures 1 to 5, inclusive, the

pressurizing unit comprises an auxiliary bellows 56 having a lower stationary head 51 and an upper movable head 59 interconnected by a flexible, im-

pervious, and preferably corrugated sleeve 59. The lower stationary head 51 of the bellows 56 is supported upon a tubular nipple 6| by means of which communication is established between the interior of the bellows 56 and the bore 62 of an air and gas inlet housing 63 upon which the nipple 6| also is supported. Extending laterally and preferably at a slight angle from the housing 63 is an arm 64 from the outer end of which preferably a pair of spaced dependent flanges 66 and 61 extend to embrace an upwardly extending flange 68 of a rigid, horizontal bar 69 of the frame- Clamping screws H carried by the flange 61, permit securing the inlet housing 63 rigidly but removably upon the frame bar 69, as clearly illustrated in Figure 2.

A bracket 72 is rigidly secured to the upper head 58 of the auxiliary bellows 56 a by a suitable fastening screw 13, and extends laterally therefrom so that a downwardly extending clamp 74 can be secured to the lever 2| of the respirators bellows actuating mechanism. As best shown in Figure 4, this clamp 14 comprises an arm 16 extending downwardly from the bracket 12 and having a flange 'l'l extending inward at its lower end. A strap 78 is carried by a screw 19 extending through both the strap 18 and the arm 16.

This screw is provided with a nut 8| engaging the outer face of the arm and a head 82 engaging the outer face of the strap 18 so that when the screw 19 is tightened into its nut 8| the strap 18 is drawn forceably toward the arm 16. The parts are so proportioned and arranged that the horizontally extending lever 2| of the respirators actuating mechanism is receivable between the flange TI and the proximal end of the strap 18, the opposed faces of which are preferably beveled, as indicated at 83 and 84 respectively, to enhance the security of their engagement upon the opposite edges of the lever 2| when the screw 19 is tightened. The head 82 of the screw 19 is provided with a convenient handle in the form of a transversely extending bar 86 permitting the tightening or loosening of the screw 19 manually and without requiring any tools.

An important consideration in this connection is that both the clamp 74 whereby the upper movable bellows head 58 is operably mounted upon the lever 2| and the arm 64 and its flanges 66 and 61 are of such simple design and are arranged so that they can so readily be secured in proper position upon their respective associated portions of the respirator proper that the pressurizing assembly 5| can be mounted upon the respirator in operative position and connected thereto for operation in synchronism with the cyclic movements of the main bellows l6 very quickly and with such facility that it is not even necessary to shut down the respirators operating mechanism. The importance of this detail lies in the fact that it is unnecessary to interrupt the operation of the respirator in order to mount my attachment thereupon for synchronized operation in conjunction therewith-a feature readily appreciated by anyone conversant with the circumstances under which poliomyelitis patients are treated in and with apparatus of this general type.

Mounted upon the inlet end of the housing 63 is an upwardly extending air inlet tube 9| upon the upper end of which is mounted a receptacle 92 adapted to receive a conventional filter pack 93. A check valve 94 below the filter pack 93 permits air to enter the housing 63 through the air inlet tube 9| but precludes escape of air through the air inlet tube 9|. Means are also provided for the entry of oxygen or other suitable gas into the inlet housing 63 as by means of a manually operable valve 96, the bore of which is in communication with the bore 62 of the housing 63. To the outer end of the valve 96 a suitable tube 91 is afiixed, this tube 9'! being adapted to be connected to an oxygen tank 95 as indicated in Fig ure 1, or other suitable source of the gas or mixture of ases which the condition of the patient to be treated indicates.

Also in communication with the bore 62 of the housing 63 is an accumulator bag 98 preferably of conventional design and composed of suitable resilient impervious material. A check valve 99 is interposed between the portion ||l| of the housing 63 into which the air inlet tube 9|, the gas inlet valve 96, and the accumulator bag 98 open into the bore 62 and the portion I02 of the bore 62 with which the nipple 6| communicates. It might here be explained that the function of the accumulator bag 98 is to permit continuous flow of the gas to be administered to the patient through the valve 96 and into the portion |9| of the housing in spite of the fact that withdrawal of this gas from the portion |9| is intermittent since such withdrawal occurs only during an expansion or suction phase of the cycle of operation of the bellows 56. During a compression phase of the bellows 56 the check valve 99 prevents reversal of flow therepast and since the valve 99 then will be closed, the gas which continues to flow inwardly through the valve 96 will be stored within the accumulator bag 98 ready for withdrawing into the portion I02 of the housing 63 when the bellows 56 enters its next intake phase. Inasmuch as most patients do not require pure oxygen, but only a mixture of oxygen diluted with a predetermined proportion of air, the valve 96 will in most cases be so regulated that the total quantity of oxygen permitted to pass the valve 96 during the period of time required for a complete cycle of operation of the bellows 56 will be substantially less than the total volume of gas which the bellows 56 is adapted to receive and expel during each of its cycles. Consequently, when the bellows 56 first begins to expand it will draw the oxygen which theretofore has been stored within the accumulator bag 98, and, due to the slight and yet material resistance to such entry of air as is offered by the check valve 94, not until all of the oxygen so stored within the bag 68 has been withdrawn will air begin to enter the system through the filter pack 93.

As a precautionary measure, a safety valve I96 resiliently pressed into closing relationship as by a spring I9? is operatively associated with a port I98 in the lower, stationary head 51 of the bellows 56. The spring lill is so designed that it will open in response to gas pressure within the bellows 66 at any time that the pressure of that gas exceeds the maximum internal pressure which safely can be permitted to be be imposed upon the patients respiratory system.

To the discharge end III of the housing 63 the supply tube 54 is connected preferably by means of a suitable coupling member H2. However, before passing through the coupling member I I2 into the supply tube 54, gas must pass through another check valve II5 the function of which is to prevent reversal of flow of gas within the supply tube 54 during the expansion phase of the cycle of operation of the bellows 56.

Also leading from the discharge end I II of the housing 63 is an auxiliary pressure tube H3, the bore of which is maintained in communication with the bore 62 through a by-pass II4 leading into the bore 62 between the two check valves 99 and H5, with the result that the pressure existing within the auxiliary tube H3 is equilibrated closely with that within the bore 62 of the housing 63 at any given time during the cycle of operation, without any resistance from the check valves.

Means are provided at the other end of the tube 54 for connecting it optionally to a facial breathing mask such as that indicated at H6 in Figure l or to a tracheotomy tube such as that indicated diagrammatically at H1 in Figure 10, depending upon the individual requirements of the patient being treated. In the modification illustrated, the connecting means comprises a tubular housing I2I best understood by reference to Figures 1, 8, and 9. This housing actually constitutes a continuation of the supply tube 54 inasmuch as it is securely and semi-permanently attached thereto as by having its inlet end I22 fitted tightly into the bore of the tube 54, thus placing the bore I23 of the housing I2I in communication with the bore of the outlet tube 54. Preferably, the housing I2I is of angular design comprising two branches I24 and I26. The branch I26 is provided with an exhaust or exhalation port I21 extending through a wall thereof parallel to the branch I24 so that a bracket I26 rigid with and extending laterally from the branch I24 extends past the outer end of the port I21. Accordingly, the bracket I28 is in convenient position to support a nipple I29 extending through the bracket I28, in coaxial alignment with the port I21. This nipple I29 is of tubular form and the auxiliary pressure tube H3 is connected to the end thereof opposite the port I21.

A hollow bulb I3I of resilient impervious material is mounted upon the face I32 of the bracket I28 which is proximal to the port I21, by having a peripheral edge I33 which defines the end of the neck I34 of the bulb I3I clamped between a head I36 on the nipple I29 and the bracket I28. The bore I31 of the nipple I29 opens into the interior of the bulb I3I with the result that communication is established between the interior of the bulb I3I and the bore 62 of the housing 63 of the pressurizing assembly 5I independently of any check valves and of the pressure control box assembly 52 which, as will be described in detail hereinbelow, is in communication with the main supply tube 54. As the result of this direct and uninterrupted connection between the interior of the bulb I3I and the bore 62 of the housing 63 the bulb I3I is delicately sensitive and substantially immediately responsive to changes of pressure created within the housing 63 in response to operation of the auxiliary bellows 56. Consequently, almost immediately upon the commencement of the pressure stroke of the bellows 56, the pressure created within the housing 63 is transmitted by the auxiliary tube H3 to the interior of the bulb I3I which is thereby expanded into closing relation with a valve seat I4I encircling the outer end of the expiration port I21. On the other hand, almost immediately upon commencement of the suction or intake stroke of the bellows 56 the bulb I3I is caused to retract, opening the port I21 and thereby establishing direct communication between the bore I23 of the housing I2I and the atmosphere. Sensitivity and immediacy of response of the bulb I3I to changes of pressure thereinside are enhanced by forming the bulb I3I to resemble a substantially wafer-like design, as clearly illustrated in Figure 9, so that that surface I42 thereof proximal to the valve seal MI is subject to being flexed outwardly in response to internal pressure much more readily than can a spherical or substantially spherical bulb be expanded.

One of the important details of the present invention is that it discharges the exhaled gases from the system at a point immediately adjacent the patient so that those exhaled gases contaminate the fresh supply of oxygen available to the patient for his next successive inhalation only throughout a minimum length of the supply tube. It is for this reason that the exhalation port I21 is arranged within the housing I2I which constitutes the outer end of the supply tube 54, i. e., the end thereof which is closest to the patient. This leaves only a minimum length of conduit interposed between the patient and that portion of the system at which actual discharge of exhaled gases to the atmosphere occurs. This length of conduit apt to contain contaminated, exhaled gases at the end of the exhalation period comprises the irreducible minimum of the conventional flexible interconnecting tube I46 carrying at its outer end an adaptor I41 conventionally employed as the means for connecting a breathing tube optionally to a breathing mask H6 or to a tracheotomy tube H1. Means are provided for releasably mounting the housing I2I in suitable location conveniently adjacent the head I2 of the patient occupying the shell II of the respirator. An extension I5I of the housing I2I carries a flange I52 at its outer end. This flange and a setscrew I53 threaded therethrough are adapted to be engaged in selected position of adjustment upon a rod I54 the upper end I56 of which is of aduncate form to facilitate its being hooked over any conveniently located protruding portion of the respirator, such as one of the clamping screws I51 whereby the respirators collar 42 is clamped in sealing position to the end I3 of the respirators shell II.

The pressure control box assembly 52 comprises a casing I6I which is hollow to provide a chamber I62 thereinside. A laterally extending flange I63 of the casing I6I is equipped with a clamp I64 at its outer end adapted to be engaged upon one of the legs 23 of the respirator, as illustrated in Figure 6, and securely, though removably attached thereto, as by a suitable manually operable setscrew I66. The flange I63 of the casing I6I also provides a convenient means for mounting a pressure gauge I61 which is operably connected to the chamber I62 by means of a suitable tube I68 so that the pressure sensitive element (not shown) of the gauge I61 is responsive to the pressure existing within the chamber I62.

Means are provided for equilibrating the pressure within the supply tube 54 and the chamber I62. A port I69 in a wall of the casing I6I leads from the chamber I62 through a collar "I to which one of the legs I12 of a tubular Y-joint, the other two legs I13 and I14 being interposed into the supply tube with the result that communication is established between the bore of the tube 54 and the chamber I62. It might be mentioned here that the leg I12 of the Y-joint I15 fits tightly into the collar IN to remain securely engaged therewith against accidental or inadvertent removal and yet can be removed therefrom when necessity for such removal arises by simply exerting sufficient manual force, drawing the Y-joint I15 away from the casing, I6I. This would permit a nurse or other attendant to remove the pressure control box from the pressure breathing system immediately should any emergency requiring such removal arise. The nurse then can place her hand partially over the exposed end of the leg I12 to regulate escape of oxygen from the Y-joint I15 and thus assure delivery of oxygen to the patient without being subject to the control of the pressure control valve which is operably associated with the control box assembly 52.

This pressure control valve is in the nature of a relief valve which automatically opens whenever the pressure within the system reaches a maximum which previously has been determined as being the pressure at which it is advisable to administer oxygen to the patient. It comprises a valve IBI carried at the outer end of a pivotally mounted arm I82 in position to engage a valve seat I83 encircling the outer end of a port I84 in one of the walls of the casing I6 I. The inner end of this port I84 opens into the chamber I62, hence this valve IBI is in the nature of a flap valve adapted to be opened, establishing communication between the chamber I62 and the atmosphere, whenever pressure within the chamber I 62 exceeds a certain value as predetermined by the setting of a spring I86 encircling the pin I81 whereby the inner end of the arm I 82 is pivotally mounted upon the casing I6I. This pin I81 is rotatably mounted in an extension I88 of the casing I6I and carries on its exposed outer end a suitable lever I89 which facilitates turning the pin I81 and thereby varying the tension of the spring I86. Consequently, the relief valve I8I is regulable to open at whatever pressure within the pressure breathing apparatus is deemed to be the maximum safe pressure at which the gases can be supplied to the patient.

Preferably, the auxiliary pressure tube H3 is disposed throughout the major portion of its length inside the main supply tube 54 so as to avoid for an operator or attendant the inconvenience of having to handle two separate tubes when mounting or dismounting the device and when tending a patient within the iron lung. However, as mentioned hereinabove, an important detail of the present invention is that the pressure created within the exhalation valve control bulb I3I should coincide quite closely at any given time during the cycle of the machine's operation with the pressure then existing within the bore 62 of the housing 83 at the opposite end of the tube, and for this reason the auxiliary pressure tube II3 should by-pass the pressure control box assembly 52. With this object in view, two ends I98 of the auxiliary pressure tube I I3 extend through the walls of the supply tube 54 closely adjacent the Y-joint I13 and these ends are interconnected by an elbow or U-shaped tube I91 attached to the Y-joint on its outer surface. Similarly, attachment of the supply tube 54 to the housing I2I of the head assembly 53 is facilitated by having the end I88 of the aux- 10 iliary tube nearest the housing I2I pass out through the wall of the supply tube I54 closely adjacent its point of attachment to the housing i2I so that it, the auxiliary tube I I3, can readily be connected to the bulb-mounting nipple I29 exteriorly of the supply tube 54.

In the same manner, the opposite end I99 of the auxiliary pressure tube H3 extends through the wall of the supply tube closely adjacent the connection of the latter to the housing 63 of the gas pressurized assembly 5|, thus enabling the end I99 of the auxiliary pressure tube H3 to be connected to the housing 63 by a nipple 2M communicating with the by-pass Il4 exteriorly of the supply tube 54 and of the coupling H2.

Operation Since the requirements of different patients afflicted with poliomyelitis vary so widely and are fraught with so many intricacies beyond the realm of ordinary engineering, that they are fully understood only by medical specialists specifically trained for the purpose, the operation of the apparatus of the present invention will be discussed here only from the standpoint of its I mechanism of the respirators principal bellows I6 is such that the one is expanded while the other is contracted, the auxiliary bellows 56 will create pressure within its associated system during each phase of the cycle when the main bellows I6 is creating negative pressure within the shell I I. Consequently, each time negative pressure is created within the shell ll, causing expansion of the patients thoracic cage, oxygen or other suitable gas or mixture of gases is supplied to the patient at positive pressure either through a facial mask H6 or tracheotomy tube H1. The spring I86 of the pressure control box assembly 52 should be so regulated that the auxiliary bellows 59 will develop and maintain for the balance of its compression stroke, pressure of oxygen adequate not only to overcome the resistance of the patients upper respiratory system, but also to thoroughly ventilate the patients lungs. It is readily apparent, however, how it is that application of gases to be breathed at positive pressure, to the patients respiratory system, i. e., internally of the patient, makes it possible to operate the main bellows I6 in such a manner as to produce a partial vacuum within the shell I I of considerably less magnitude than when the gases to be breathed by the patient are supplied only at atmospheric pressure.

Since both the main bellows I6 of the respirator and the auxiliary bellows 56 of my attachment therefor are operated by the same actuating mechanism, their positive synchronization of each other is assured so that when the main bellows I6 is creating a negative pressure the auxiliary bellows 56 is creating a positive pressure, and vice versa. Upon termination of the negative pressure stroke of the main bellows I6 and commencement of its positive pressure stroke, the auxiliary bellows 56 will commence its negative pressure stroke. The lowered pressure thus created within the casing 63 of the pressurizing assembly 5| will substantially instantaneously be transmitted to the interior of the exhalation valve I3I, causing the valve to open the port I21 and permitting the patient to exhale easily and naturally to the atmosphere through only a minimum length of conduit. As explained hereinabove, this will leave fresh uncontaminated gases so closely adjacent the patient that only an immaterial quantity of exhaled gases will have to be taken into his respiratory system before the fresh, pure gases reach him at the beginning of his next inhalation phase.

During the phase of the cycle when the auxiliary bellows 56 is expanding it will first draw all of the oxygen which has been stored within the accumulator bag 98 and thereafter throughout the remainder of its intake phase the bellows 56 will draw fresh air into the system throughout the filter pack 93. Upon termination of this phase, the bellows 56 will start to contract, raising the pressure within the system, closing the checkv valve 99, and forcing the gas throughthe opened check valve II3 through the supply tube and to the patient, all this occurring while the mainbellows I6 is expanding and creating negative pressure within the shell II externally of the patient. Also while this is occurring the positive pressure which exists within the housing 63 of the pressurizing assembly l is transmitted through the auxiliary pressure tube II3 to the bulb valve I3I, thus closing the port I21 and thereby assuring that the gases will be supplied to the patient internally at positive pressure. However, immediately upon commencement 'of the intake phase of the bellows 56 negative pressure will be created within the housing 63 and this, being transmitted through the auxiliary tube M3 to the bulb I3I, will open the exhalation port I21, permitting the patient to exhale substantially directly to the atmosphere as hereinabove explained.

The pressure control assembly 52 maintains the pressure for which the apparatus has been setby regulation of the spring I86, throughout the inspiratory phase but any excess volume of air or oxygen is blown off through the relief valve I8I. Consequently, air or other gases are never forced into the patients lungs beyond that expansion which the pressure for which the spring I86 and the negative pressure then existing within the shell I I, operating jointly with each other, will produce. As a precautionary measure, the valve 96 should be so adjusted as should also the length of stroke of the bellows 56 that a small quantity of the gases being administered will spillout through the relief valve I8I during each cycle, i. e., the stroke volume should be adjusted slightly to exceed the patients requirements.

Under some conditions, it is desirable or necessary toinstall the respirator accessory without stopping the action of the respirator. This can be accomplished readily if certain precautions are taken. By compressing the auxiliary bellows 56 the bellows actuating bracket 12 can be slipped into place upon and fastened to the respirator level 2I and then the main base bracket 64 can be attached on the bar 69 of the respirator frame. The bracket I4 should then be adjusted along the lever 2I so as to assure the proper stroke for the bellows 56 as hereinabove explained. As long as the stroke volume is sufficient to produce some overflow out through the relief valve I8I of the control box assembly 52 at the end of each inspiratory phase of the cycle, the bellows stroke is adequate.

fWhen-it proves to be desirable to open the shell II of the respirator for nursing or other care, the positive pressure being. administered by the respirator attachment should be increased by proper manipulation of the lever I89 associated with the spring I86. This is one of the more important features of the present invention because it greatly facilitates performing those services for the benefit of the patient which require temporary discontinuance of the operation of the respirator proper.

I claim:

'1. In combination, a respirator comprising a shell adapted to receive the chest of a patient and means for alternately lowering and then raising the pressure within said shell according to a predetermined cycle; and pressure breathing apparatus comprising a source of gas to be breathed,a supply tube leading therefrom, means for connecting said tube to the patients respiratory system, a pump for intermittently raising the pressure of said gas within said tube, and means for connecting said pump to said respirators pressure-varying means to be operated thereby and synchronously therewith, said connecting means being adjustable to attain variation of the stroke of said pump and of the vol u-metric output thereof.

2. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a, member movable with respect thereto for alternately drawing gas into said bellows and ex pelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said' bellows movable member to said respirators pressurecreating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, and means for connecting said supply tube to said patients respiratory system.

An accessory for a respirator comprising a shell adapted to receive. the chest of a patient andmeans for alternately creating negative and then positive pressure within said shell according ,to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and 'a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting saidbellows stationary member on said respirator, means for operably connecting said bellows movable member to said respiratorspressure-creating means to be operated thereby, means for connecting said bellows to asource of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, means providing. a pressure-relief port establishing communication between the interior of said supply tube and the atmosphere, a valve seat encircling the outer end of said port, a flap valve operably associated with said seat, and a spring. yieldably pressing saidval-ve against said seat to resist escape of gas fromsaidtube through said port.

4-. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive; pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressure-creating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, means providing a pressurerelief port establishing communication between the interior of said supply tube and the atmosphere, a valve seat encircling the outer end of said port, a flap valve operably associated with said seat, a spring yieldably pressing said valve against said seat to resist escape of gas from said tube through said port, and means for adjusting said spring to vary the pressure of gas within said tube necessary to unseat said valve.

5. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressure-creating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, pressure control means comprising a hollow box, means for connecting said tube thereto to establish communication between the interior of said box and the interior of said tube to equilibrate pressures therein, a port leading through a wall of said box, a valve port, an arm pivoted at one end for movement about an axis offset from said valve seat, a valve carried by the other end of said arm in position to engage said seat, a-spring associated with said arm and yieldably pressing said valve onto said seat to resist escape of gas from said box through said port, and means for adjusting said spring to predetermine the pressure of gas within said box at which said valve will be unseated.

6. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressure-creating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, said supply tube having a port in the wall thereof opening to the atmosphere from said tubes interior and disposed closely adjacent the outer end of said tube, a

valve operatively associated with said port, and,

a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressurecreating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, said supply tube having a port in the wall thereof opening to the atmosphere from said tubes interior and disosed closely adjacent the outer end of said tube, a valve operatively associated with said port, and means operative in response to fluctuation of pressure within said tube for holding said valve closed during the gas-expelling phase of said bellows operating cycle and for holding said valve open during the intake phase of said cycle.

8. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure Within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mountin said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressure-creating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, said supply tube having a port in the wall thereof opening to the atmosphere from said tubes interior and disposed closely adjacent the outer end of said tube, a valve operatively associated with said port, and means operative in response to fluctuation of pressure within the portion of said tube adjacent said bellows for holding said valve closed during the gas-expelling phase of said bellows operating cycle and for holding said valve open during the intake phase of said cycle.

9. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressurecreating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system comprising a tubular casing connected at one end to said supply tube and adapted at its other end for connection to the patient, said casing having a port therein opening from said casings bore to the atmosphere, a valve seat encircling the outer end of said port, an arm rigid with said casing and extending adjacent said port, a hollow bulb of flexible material carried by said arm in position normally spaced outwardly from said seat, and an auxiliary tube establishing communication between the interior of said bellows and the interior of said bulb whereby gas is forced into said bulb and said bulb is expanded into closing relation with said seat at the beginning of the gas expelling phase of said bellows" cycle of operation and whereby gas is withdrawn from said bulb and said bulb is collapsed into port-opening relation at the beginning of the intake phase of said cycle.

10. An accessory for a respirator comprising a shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said. bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressurecreating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, means providing a pressure-relief port establishing communication between the interior of said supply tube and the atmosphere, .a valve seat encircling the outer end of said port, a flap valve operably associated with said seat, a spring yieldably pressing said valve against said seat to resist escape of gas from said tube through saidport, means for adjusting said spring to vary the pressure of gas within said tube necessary to unseat said valve, said supply tube having an exhalation port in a wall thereof opening tothe atmosphere from said tubes interior and disposed closely adjacent the point of connection of said tube to said patients respiratory system, an exhalation valve operatively associated with said exhalation port, and means operative in response to fluctuations of pressure within said tube adjacent said bellows for holding said exhalation valve closed during the gas-expelling phase of said bellows operating cycle and for holding said exhalation valve open during the intake phase of said cycle.

11. An accessory for a respirator comprising a 16 shell adapted to receive the chest of a patient and means for alternately creating negative and then positive pressure within said shell according to a predetermined cycle, said accessory comprising a bellows comprising a stationary member and a member movable with respect thereto for alternately drawing gas into said bellows and expelling said gas therefrom, means for mounting said bellows stationary member on said respirator, means for operably connecting said bellows movable member to said respirators pressurecreating means to be operated thereby, means for connecting said bellows to a source of gas to be administered to said patient, a supply tube leading from said bellows, means for connecting said supply tube to said patients respiratory system, means providing a pressure-relief port establishing communication between the interior of said supply tube and the atmosphere, a valve seat encircling the outer end of said port, a flap valve operably associated with said seat, a spring yieldabl pressing said valve against said seat to resist escape of gas from said tube through said port, means for adjusting said spring to vary the pressure of gas Within said tube necessary to unseat said valve, said means for connecting said supply tube to the patients respiratory system comprising a tubular casing connected at one end to said supply tube and adapted at its other end for comiection to the patient, said casing having an inhalation port therein opening from said casings bore to the atmosphere, a valve seat encircling the outer end of said inhalation port, an arm rigid with said casing and extending adjacent said inhalation port, a hollow bulb of flexible material carried by said arm in position normally spaced outwardly from said seat, and an auxiliary tube establishing communication between the interior of said bellows and the interior of said bulb whereby gas is forced into said bulb and said bulb is expanded into closing relation with said seat at the beginning of the gas expelling phase of said bellows cycle of operation and whereby gas is withdrawn from said bulb and said bulb is collapsed into port-opening relation at the beginning of the intake phase of said cycle.

VIVIAN RAY BENNETT.

References Cited in the file of this patent UNITED STATES PATENTS Number 

